We have a Blue-ray player....but have yet to watch a Blue-ray movie. This will change soon.
Netflix offers Blue-ray movies for just $1 extra per month. Once I added the Blue-ray option all movies in our que there were available on Blue-ray were set up for that format. Some of the movies that were "long wait" were now "short wait" or available "now". Nice. Most of the homes in the United States have plain "old" DVD players. Blue-ray is still an emerging format. Only within the last 6 months has a Blue-ray player been available under $300. Previously the most inexpensive Blue-ray player was the PlayStation 3 at $399. I think Blue-ray players will be under $150 within a year.
Unlike DVD there are many types of Blue-ray players available. The basic players (Profile 1.0)....play movies. The next step up (Profile 1.1) play movies and have can access special features on the disc. The final step (Profile 2.0) plays moves, can access special features, has on-board storage of at least a gigabyte of memory AND can go on the internet. Most people will likely choose the basic player...as it's the cheapest.
The player we have is the top level Profile 2.0 player. I am very happy with it. The Netflix integration is great. We can easily watch movies on DVD, Blue-ray or over the internet....all from Netflix....no extra cost beyond our monthly fee.
One thing the Blue-ray player (and many newer regular DVD players) can do is upconvert regular DVDs. DVD's are recorded at 480P. That means there are 480 lines of resolution. HDTV's are with 720P or 1080P. Up-converting means taking a regular 480P DVD and making it a 720P or 1080P DVD depending on what the TV can take. In easy terms...up-converting often makes regular DVD's look amazing....high definition like.
Our first two real Blue-ray movies are in the mail. We have The Dark Knight and Step Brothers on the way from Netflix.